Post by omnipotentvoid on Apr 10, 2017 12:18:29 GMT

1. Intro (pseudo abstract):Over the past couple of years, I have played quite a few games that implement vehicle construction (most notable CoaDE, From the Depths, KSP with BDArmory and Gmod with the ACF addon). One of the major problem in these games(/mods) is figuring out how effective or efficient a specific weapon is. There is no natural metric for either of these properties, nor is there any easy metric that gives any reasonable measurement of either. My goal is to create metrics for both properties that is both reasonably easy to use (read: make a spreadsheet where variables are plugged in and an answer pops out) and reasonable accurate (read: if one weapon is better than an other as per the metric, it will perform better in that category in most situations than the other weapon).The distinction between efficiency and effectivity, in this case, is (essentially) that effectivity is per encounter/engagement and efficiency stretches multiple encounters/engagements. As an example: a coilgun that accelerates kg scale projectiles to ~75% of c at an energy efficiency of ~40%. This weapon is fairly effective: capable of destroying almost all opponents in a single hit, hard to dodge due to high projectile velocity, energy and mass efficient and near impossible to intercept. It is also extremely inefficient: the mass of the weapon means it requires immense amounts of fuel to move and retarget. It is also slow to target making it hard to switch between targets that approach from different directions. Etc.

These metrics must take into account properties that can be (and traditionally are) split into three categories:

Internal Ballistics

External Ballistics

Terminal Ballistics

Note: Ballistics as used here refers to the properties that the projectile has in explosively propelled projectile weapons and in the case of internal ballistic also some properties of the weapon. From here on I will use these to refer to both weapon an "projectile" (this includes laser beams and missiles) properties, simply because I have become used to using these terms.

2. The Categories/PropertiesAs discussed in the intro, the properties, these metrics must be derived from, can be split into three major categories as shown below. Properties derived from stated properties are not listed (will list them if enough people request it and the properties are subject to change):2.1Internal BallisticsThese are the properties of the weapon an projectile as the weapon is fired/targeted/moved.

weapon mass

weapon dimensions

static power use

active power use

energy used to fire projectile

projectile mass

projectile dimensions

exit velocity

projectile impulse

projectile energy

effectivity/efficiency metric of warhead(/shrapnel)

waste heat produced

fire rate

note: a warhead is counted as its own weapon and its efficiency/effectivity effect the metric of the weapon that uses it. The same is true for shrapnel created by explosives: the count as "weapons fired by the warhead".

2.2 External Ballistics

These are the properties of the projectile and weapon that describe targeting/accuracy and flight of the projectile.

2.3 Terminal BallisticsThese are the properties that determine what happens when the projectile hits (basically damage).

projectile dimensions

distribution of energy across target

projectile mass

projectile energy

projectile impulse

projectile velocity

impact energy conversion ratios

note: projectile mass and dimension only applies to kinetic projectiles. Laser, radiation and blast damage are based of the distribution of energy across target.

This is more or less as far as I've gotten. I have started on working out the interaction of the properties in the terminal ballistics part of the metric for effectivity and will post it as soon as I consider it presentable. I feel fairly confident in figuring out how these properties interact, but am currently at a loss as to how to express this in term of numbers. Any help is appreciated.

Post by Enderminion on Apr 10, 2017 13:23:52 GMT

some weapons are not designed to do the most damage over the largest area, some weapons have diffferent goals for which they are very effective, also aside from projetile impulse, impact energy conversion ratios, and effectivity/eficiency metric, all of these stats are in game. also velocity over time is useless, there is no drag to slow shots down and Dv is sufficent for missiles/drones

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Post by omnipotentvoid on Apr 10, 2017 14:31:37 GMT

some weapons are not designed to do the most damage over the largest area, some weapons have diffferent goals for which they are very effective, also aside from projetile impulse, impact energy conversion ratios, and effectivity/eficiency metric, all of these stats are in game.

What is listed in game are statistics. A metric would take these as inputs and output a number. As for the different goals: all weapons (not just in CoaDE) are designed to do the same thing. Essentially weapons attempt to disrupt the structure of a target to the point it becomes none functional. A weapons ability to do this depends on the properties listed in 2.3 and properties derived from them.This can never be a perfect representation of a weapons ability (since this relies on tactical situation and target as well) but it should be adequate given a limitation on certain parameters. This is what I meant when I said that there is no natural metric. In other words: given a set of weapons with certain constraints (mass, energy use, limited space) these metrics should be fairly good at determining which is best.

Post by omnipotentvoid on Apr 10, 2017 15:35:21 GMT

No, I actually realized I used the wrong term. What I want to make is a sort of what would be called (mathematically) a measure in English (sort of as in I'm not being completely mathematical accurate with what I'm doing). Basically, I'm looking at the properties of a weapon as "parts of vectors", essentially making a set out of weapons described as vectors of their properties. The "metric" I'm creating is technically a function that defines "length" in this set of vectors, giving each possible weapon in the set a positive real value. The way this function is set up, it should give higher values to weapons that tend to perform better in terms of efficiency and effectivity respectively (I'm talking about two different function here). In order to make such a function, I have to work out how all the properties interact.

Post by AdmiralObvious on Apr 10, 2017 18:05:33 GMT

What I'm more interested in if we get these metrics, is the effectiveness of specific, namely kinetic weapons against different types of armor. You might be covering this under impulse, but one thing I've always wanted to figure out is how well will a weapon perform assuming a 100% chance to hit the mark it was aiming for. If the shot doesn't penetrate, will it cause spall? If it does penetrate, does it vaporize or penetrate fully, or something in between?

I am very much interested in what you got planned here however, and am as much at a loss as you in figuring out numbers to show for a project like this.

Post by omnipotentvoid on Apr 10, 2017 18:27:11 GMT

What I'm more interested in if we get these metrics, is the effectiveness of specific, namely kinetic weapons against different types of armor. You might be covering this under impulse, but one thing I've always wanted to figure out is how well will a weapon perform assuming a 100% chance to hit the mark it was aiming for. If the shot doesn't penetrate, will it cause spall? If it does penetrate, does it vaporize or penetrate fully, or something in between?

I am very much interested in what you got planned here however, and am as much at a loss as you in figuring out numbers to show for a project like this.

Also, isn't static energy irrelevant?

The metric is for the weapon only. How it does damage varies by target, but is always dependant on impulse and energy. There will be a lot more on this in the terminal ballistics chapter, but that's not ready yet.

Post by acrosome on Apr 11, 2017 5:07:12 GMT

Pretty much, the answer is "It can't be done." Various people have been trying to produce some sort of scientific absolute measure of weapon effectiveness literally for centuries, without success. Which in itself isn't really an indicator that it can't be done, but is at least strong evidence that it's probably too complex an issue to be solved by some dude on the internets. Hint- it's more than just energy delivery. It's complex. As a trivial example, one weapon will be better at penetrating armour, while another will be able to do much more damage to a lesser-armoured target. You can definitely compare weapons, or produce armour-penetration tables if that's what you want, but you can't boil every weapon down to some sort of single number. How would you score a sword against a rocket launcher?

Yes, you can produce some sort of model from the factors you listed. All models are imperfect... but some are useful. But, Jesus, look at the number of factors you could produce just off the top of your head with little or no research. It's complex. Then, add in target factors. Or, looked at another way, the entire CoaDE engine is an attempt to do what you are trying to do. No reasonably accurate model can be simpler. More helpful (for most people) might be a short primer on the various types of weapons and what the statistics about them mean. "All other things being equal, a more powerful laser with a larger aperture and smaller spot size is better", etc. But larger spots might have better hit rates when sniping enemy lasers... See?!? It gets complex. If your target is a laser-only armed ship then different weapon choices are best, compared to a target with a different design philosophy.

Heck, we don't even have a useful way to compare weapons in the same class, such as handguns*, because target factors, let alone compare lasers to coilguns to nukes.

*Every "handgun stopping power" metric that you have ever heard of is crap, so please don't try to cite one to me. In fact, the moment someone says the term "stopping power" you should probably conclude that they have nothing productive to say on the subject at all. There has been exactly one reasonably scientific approach made to this issue, and above a certain minimum cartridge size/power the only factor that seems to matter is how many times you hit the guy. I will avoid clogging this forum with further explanation, but I do want to head off the pointless objections that I can see coming. I'm a military trauma surgeon, and yet any time someone asks me a question on just one small aspect of this subject my answer is always "I'd have to get a grant and go shoot a thousand goats to answer that."

So. About the only option you have is to resort to empirics. Run a few tens of thousands of CoaDE battles and analyse the outcomes, and see if anything significant pops out. And then it will all change with the next update...

Post by subunit on Apr 11, 2017 5:50:10 GMT

*Every "handgun stopping power" metric that you have ever heard of is crap, so please don't try to cite one to me. In fact, the moment someone says the term "stopping power" you should probably conclude that they have nothing productive to say on the subject at all. There has been exactly one reasonably scientific approach made to this issue, and above a certain minimum cartridge size/power the only factor that seems to matter is how many times you hit the guy. I will avoid clogging this forum with further explanation, but I do want to head off the pointless objections that I can see coming. I'm a military trauma surgeon, and yet any time someone asks me a question on just one small aspect of this subject my answer is always "I'd have to get a grant and go shoot a thousand goats to answer that."

Post by Enderminion on Apr 11, 2017 11:17:21 GMT

*Every "handgun stopping power" metric that you have ever heard of is crap, so please don't try to cite one to me. In fact, the moment someone says the term "stopping power" you should probably conclude that they have nothing productive to say on the subject at all. There has been exactly one reasonably scientific approach made to this issue, and above a certain minimum cartridge size/power the only factor that seems to matter is how many times you hit the guy. I will avoid clogging this forum with further explanation, but I do want to head off the pointless objections that I can see coming. I'm a military trauma surgeon, and yet any time someone asks me a question on just one small aspect of this subject my answer is always "I'd have to get a grant and go shoot a thousand goats to answer that."

*uses CoaDE engine to resolve 9mm vs .40 vs .45 debate*

*10mm FTW

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